The maximum resolution of Android is a popular misunderstanding as far as I can tell. The Android SDK's emulator is limited in resolution, though the OS guidelines have three distinct 'sizes' and 'densities' that are allowed, one of which is 'large screen' that has been supported since v1.6 (IIRC). In any event, I'm quite certain that no special hackery has been required for the Galaxy Tab to display at 1024x600, or the Toshiba AC100 for that matter.
I would argue that Android's 'market fragmentation' is much lower than that of Apple's, in that up until this point Apple's support across devices is largely limited to the device itself. Android binaries on the other hand span multiple OS's, and multiple devices quite well. It's clear that the OS design bore this in mind from the outset. For example, properly developed apps display work flawlessly on the Tab, though often with phone-esque UIs.
I suspect that Gingerbread/Honeycomb will feature a more flexible UI for larger screens, but ideas like 'fragmentation' and android not being 'tablet ready' are ideas popularized by modern media, but are no moreso than any other OS out there. In fact, I'd argue that due to Android's design, it's far less subject to 'fragmentation' than other mobile OSs.